From the past, as medicines that are difficult to store in a drug solution state, items are known that are kept sealed in a vial in a powder or dry state and prepared by dissolving immediately before use.
However, when preparing this kind of drug solution, first, a vial in which the medicine is housed and a syringe in which a solution is filled are prepared, and the needle of the syringe is pierced through the rubber stopper that seals the mouth of the vial. Then, after the medicine for which the solution has been injected into the vial from the syringe is prepared by dissolving inside the vial, the obtained drug solution is collected by suction with the syringe.
Then, the syringe that collected the drug solution is separated from the vial by pulling away the injection needle from the rubber stopper, and this is used for a mixed injection or the like of a drug solution to a transfusion container or line.
However, when pulling the injection needle out from the rubber stopper, there is the risk that drug solution inside the vial or the drug solution that was adhered to the injection needle or the like will go out to the external space in a spilled, splashed, or aerosol state. In particular, medicines kept sealed in a vial are sometimes items with high toxicity such as antitumor drugs or the like, and if that kind of drug solution leaks to the external space or the like, there is a problem of an adverse effect on the bodies of the medical staff, patients, or the like.
In Japanese Patent Republication No. JP-B-5-088142 (Patent Document 1), proposed is confining the drug solution that leaks in the sealed space inside the over cap when pulling out the injection needle from the rubber stopper of the vial by covering the mouth of the vial with an over cap made of rubber and mounting it. However, even when this kind of over cap is mounted, drug solution adheres to the injection needle pulled out from the over cap, and it is difficult to prevent it from leaking to outside the over cap or the like, and it was not possible to obtain a satisfactory effect.